Yeah, I have major probs with stuff vanishing from my inventory.
Especially leaving Jonno's dungeon at the beginning - I have to remember never to put magic bullets in Jaheira's middle 'quiver' slot, 'cos whatever is in there just disappears. This is in addition to various seemingly random items from my inventory. Also happened in Planar Sphere - but it was my familiar that vanished - he had been all safely tucked up in my pack, but when I got back to the slums - no familiar. I hadn't lost constitution or the extra HP though. I just conjured myself up a new one!
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Time is an illusion. Lunchtime doubly so.
Epona of The Laughing Hyenas.